Hi All,
Relatively new user here and while I have nearly everything in LibreNMS set up and working I can’t seem to get the Arp Table (Overview->Arp Tables) to populate with any data whatsoever. (“No results found”)
IPV4/IPV6/Mac Address/FDB tables are all populating just fine.
I have a combination of switches, routers, windows and linux servers, printers and wireless base stations being monitored yet none of them seem to populate the ARP table.
I can’t seem to find documented exactly what needs to be turned on (if anything) to make the Arp table populate.
In the global configuration in the gui I have:
discovery_modules.arp-table true
discovery_modules.discovery-arp false
I did recently disable discovery-arp because as I understand it enabling this allows LibreNMS to find other devices not within the scan range by looking at the arp table of devices it does know about - which I don’t want it to do.
In any case the ARP table was already empty before I disabled this setting.
I did find this very old ticket:
And when I try the example snmpwalk commands on one of our switches it is returning arp table data:
/usr/bin/snmpbulkwalk -v2c -c public -Oq -m IP-MIB -M /opt/librenms/mibs udp:10.0.2.1:161 ipNetToMediaPhysAddress
IP-MIB::ipNetToMediaPhysAddress.5121.10.0.0.0 ff:ff:ff:ff:ff:ff
IP-MIB::ipNetToMediaPhysAddress.5121.10.0.0.5 0:1d:aa:aa:8a:e0
IP-MIB::ipNetToMediaPhysAddress.5121.10.0.0.220 40:b0:76:dc:ba:20
IP-MIB::ipNetToMediaPhysAddress.5121.10.0.0.254 b4:96:91:40:a3:80
IP-MIB::ipNetToMediaPhysAddress.5121.10.0.2.1 10:62:eb:af:84:0
IP-MIB::ipNetToMediaPhysAddress.5121.10.255.255.255 ff:ff:ff:ff:ff:ff
/usr/bin/snmpbulkwalk -v2c -c public -Oq -m IP-MIB -M /opt/librenms/mibs udp:10.0.2.1:161 ipNetToPhysicalPhysAddress
IP-MIB::ipNetToPhysicalPhysAddress.5121.ipv4."10.0.0.0" ff:ff:ff:ff:ff:ff
IP-MIB::ipNetToPhysicalPhysAddress.5121.ipv4."10.0.0.5" 0:1d:aa:aa:8a:e0
IP-MIB::ipNetToPhysicalPhysAddress.5121.ipv4."10.0.0.220" 40:b0:76:dc:ba:20
IP-MIB::ipNetToPhysicalPhysAddress.5121.ipv4."10.0.0.254" b4:96:91:40:a3:80
IP-MIB::ipNetToPhysicalPhysAddress.5121.ipv4."10.0.2.1" 10:62:eb:af:84:0
IP-MIB::ipNetToPhysicalPhysAddress.5121.ipv4."10.255.255.255" ff:ff:ff:ff:ff:ff
Another switch I tried does not support ipNetToPhysicalPhysAddress but does support ipNetToMediaPhysAddress.
What am I missing here ? I’m struggling to find good documentation for some of the discovery and poller modules and I note that while there is an arp-table discovery module there isn’t an arp-table poller module ?
Does this mean the arp table (if it was working) would only update 6 hourly with the autodiscover scan and not every 5 minutes with the poller ?
Any help appreciated as I just can’t figure this out.
